In reduction cells used for the production of aluminum, the carbon-based anode blocks are consumed relatively more rapidly than the cathode blocks. Accordingly, the anode region of such cells requires relatively more frequent servicing. Current is carried to the anode blocks via anode rods, each generally having a yoke which has protrusions. These protrusions are called anode stubs or anode nipples. The anode blocks are contacted via these stubs. For proper contacting to occur, the stubs must fit into receiver boreholes in the anode blocks.
In the more common arrangements, the anode rods have three adjacent and parallel stubs (two "outer" stubs and an "inner" stub) disposed in one plane or two sets of three anode stubs in parallel arrangement. When aligned, all of the stubs are parallel to the anode rod. The anode rods are often constructed of aluminum, while the stubs are often constructed of steel or cast steel.
When the anode blocks are replaced, the anode rods must be serviced by stripping off caked material from the alumina/aluminum bath. More importantly, due to the large temperature gradients which occur during the operation of the cell, the stubs are often deformed during the course of operation of the cell. These deformed stubs must be repaired so that the anode rod can be coupled to the replacement anode block. Usually, when the outer stubs are deformed, they are bent towards the inner stub (or in some arrangements, towards the inner stubs). The customary repair process has been to sever the deformed stubs and to weld new, correctly aligned stubs in their place.
German patent 35 41 504 discloses equipment for checking anode rods for breakage or for alignment problems. However, this equipment cannot be used to correct any bent stubs which it may detect.